TheSkySearchers

I just received my "slightly used" Bresser AR102S "Comet Hunter" (OTA only) from Telescope Warehouse yesterday. The intent for purchasing this OTA was to have a very portable (fit in a suitcase) and sizeable Grab & Go scope. This is an inexpensive OTA, only $125.00. So my expectations were geared accordingly













It was boxed well enough but the ES finder foot had the plastic retaining screws screwed in place and the screw heads were sheared off during shipping. I emailed Bill Vorce of Telescope Warehouse and the replacement screws are already in the mail. Really not that big a deal.

The Bresser AR102S Comet Edition is a 102mm f/4.5 (FL=459) rich-field refracting telescope. And as you can see from the photo, it’s not your normal refractor configuration. Instead of having the focuser aligned with the objective at the back end of the tube, the focuser is mounted on the side of the tube. Just like you would find in a Newtonian reflector because it uses a reflector-style secondary mirror* to bounce the light from the objective lens to the eyepiece. This makes for a very short, compact scope, and theoretically, should allow for easy collimation via that secondary mirror (I haven’t tried that yet). Scopes like this are sometimes called “reflactors” because they combine an objective lens with a secondary mirror.

The OTA is 20″ long and 4" in diameter and 4 1/4″ of the 20" length is dew shield. It weighs in at a reasonable 6.1 lbs. In the pictures, you can see there is a dovetail on one side of the OTA, and there is a shoe for a finder (not included) on the other side of the OTA. Having the dovetail on one side and the finder shoe on the other is convenient because it means the OTA can’t roll over and bang the focuser if you set it down on a flat surface.

The focuser is a single-piece aluminum casting rack and pinion style which allows only 1.25" EPs. The focuser does have two features of note. First, it wraps tight to the 4″ diameter tube. Second, and more importantly, the focuser knobs point across the tube on this scope as opposed to down the length of the tube, this feature may prove to be a key feature once I start using this OTA. Again, the focuser is a single chunk of aluminum (not plastic) – the 2″ tube (also aluminum) can’t be separated from the base, nor rotated relative to it. Additionally, the 1.25" EP holder does unscrew (meaning it's threaded) so I'm looking for a way to use a 2" EP adapter on this scope but since it is a dedicated 1.25" EP scope, there is no adapter offered by Bresser or ES.

I received no collimating instructions or users manual from the seller (no biggie). So I contacted Explore Scientific and they promptly emailed the collimating instructions and the users manual.

As usual, since receiving this new scope, there is not a star to be found so I'm still waiting to perform the first light. But the daytime use shows a crisp image edge to edge. I think the contrast could be better but I'll wait on that judgment. Additionally, I've read that this scope has no baffles and would greatly benefit by flocking the inside of the OTA. I'm looking at material for that right now. As far as the first light -- standby,...

Cheers,
JT

* Existential telescope question: is it still a secondary mirror if there’s no primary?

I can't see your images, JT.

Lowjiber wrote: ↑Mon May 06, 2019 12:14 pm I can't see your images, JT.

It's a 'before I crashed the server' post.

Here are the images. I'll try to do them "inline" with a <CR> between them. Here goes. And the winner is? Can anybody else see these images? Well, 6 attached images didn't work. I'll try 5 and see what happens.

Thanks,
JT

Nicely packaged, all that bubble wrap...

I see all.
Please don't pop the bubble wrap ! :-)

Images are all there JayTee. Very curious to read how first light went!

I am looking forward to how this scope will perform! Please keep us informed JT?

Congrats on the new glass JT! Are those 3 screws on the back end for mirror collimation?

What mount you will put it on?

I dont’ know why this thread died before we got to the good part so I’ll through in my two cents.

I’ve been using my Bresser AR102S “Comet Hunter” 102mm, f/4.5 achromatic refractor extensively since September of this year. I was looking to upgrade my old scope and almost nothing else was in stock during the COVID times at the time. I love it for it’s build quality, performance, and light weight. I can easily take it anywhere. The alt/as mount is smooth, stable, and great for manually star hopping to your target. The optical quality is good and chromatic aberration is only noticeable on the Moon and Jupiter. I consider the CA to be mild compared to others I’ve seen. For Messier objects and the Andromeda Galaxy I find them looking great within the resolution of 102mm of aperture. With the included Bresser 20mm 70 degree wide eyepiece everything looks great with only minor astigmatism on the outer edges. The images are crisp and clean all the way to the edges with all of my Plossl eyepieces.

Last night my son Wes and I went to the Fort Richardson State Park near Decatur, Texas and had a blast. My skies in Fort Worth are about a Bortle 8 so it is nice to get out away from it every now and then.

Steve Yates

Cheers for resurrecting the thread Steve!

Welcome to the forum.

Regards

Graeme

Thanks, Steve,

I live on a very cloudy island. I literally have not used this scope since December a year ago.

Thanks again,
JT

Thanks JT.

I'm sorry the hear about your clouds. Here in north Texas we are often blessed (more like cursed because it means months without rain) with many endless days of cloudless nights. I just have neighbor's and city lights to contend with at home.

I was waiting to read the rest of the story before I purchased this scope but at the time I really didn't have much of a choice anyway since every larger telescope I'd get my heart set on was no longer available or back logged until who knows when. I will say again that I've been very happy with the whole setup. I see that it usually retails for $499 but I got it during a "Deal of the Day" from Adorama for $249! I definitely feel that I got my money's worth. The optics are good for a fast achromat. I can take it outside and set it up in about 2 minutes if I take my time. :-) I often come home from work, eat supper, watch a show with my wife, take the telescope out for an hour or so and then go to bed, repeat. I'm a true believer that the best telescope is the one that gets used. I have a couple of others that live in the closet. I'm also a believer in and practitioner of the KISS principle.

Steve

I bought this scope on a spur of the moment decision because it was being offered from Telescope Warehouse used for $125 - How could I pass that up. After receiving it, I did not like the star shapes it was displaying, they looked like little diamond 4-sided kite shapes. So I sent it to ES for diagnosis and potential fix - which they did and charged me NOTHING for their service, plus they paid for the shipping back to me here in Hawaii. How can you beat that for customer service? Anyway, stars are now perfect little dots and the scope is a great G & G scope on my SLT goto mount.

Cheers,
JT

Ah yes, the infamous "Newtonian" that people use "backwards" in SciFi movies.

Ha, it does look like JayTee! Maybe that’s why I’ve gotten funny looks while using it.

Steve

One thing about that scope, you don't have to worry about having too big of a secondary mirror interfering too much with the optical train.

ES indeed has great customer service. I called them when I was trying to assemble my Twilight II mount and they gave me some helpful hints as I had been trying to install the pier extension upside down. That, plus a few pics Bryan posted set me straight.